The present invention relates to various electronic apparatus including a notebook type personal computer, and more specifically, to a portable electronic apparatus used by opening a lid.
Electronic apparatuses such as a notebook type personal computer (notebook PC) comprise a power saving (power management) function to appropriately reduce or stop a power supply to an electric circuit in accordance with the usage of a system. The power management function includes a sleep function to turn off a backlight of a liquid crystal display device (LCD) and stop operations of a CPU and a hard disk drive (HDD). In addition to the sleep function, the power management function includes a suspend function to stop a power supply to peripheral apparatuses and the like so as to use the minimum amount of power required to retain data. The power management function further includes a hibernation function to turn off a power supply to the computer, while automatically saving the contents of an operation performed until immediately before the turnoff, to an HDD. The suspend stops the CPU, LCD, HDD, and the like to minimize power consumption. However, with the suspend function, unlike the hibernation function, power remains supplied to a RAM. Accordingly, a little power is consumed.
The power management function is not very convenient to users. For example, when the suspend mode is set while an expansion device such as an option card is being used, the option card and the like must be initialized for each software driver after a resume (the power supply is turned on to resume an operation starting with the last state) process. A long time is required before the system can be recovered during the resume. Thus, a conventional technique described in a patent publication is disclosed which falsely powers off the system with these devices operative to instantaneously recover the system (see, for example, Patent Document 1).
Once the suspend has been entered, when the input of a password is required during resume, usability (operability) may disadvantageously be degraded. Thus, another technique described in a patent publication enables a task to be instantaneously resumed without requiring the input of a password during the resume if the user reacts by executing key inputs a relatively short time after a shift to the suspend has occurred (see, for example, Patent Document 2). Moreover, in connection with the power management function, a technique has been disclosed which shifts to a sleep state when a lid is closed, while shifting to a hibernation state when the apparatus is lifted, in order to save time required to save or recover the state (see, for example, Patent Document 3).
[Patent Document 1] Published Unexamined Patent Application No. 9-114566 (p. 8, FIG. 7)
[Patent Document 2] Published Unexamined Patent Application No. 9-34577 (p. 9, FIG. 5)
[Patent Document 3] Published Unexamined Patent Application No. 2001-42978 (p. 7, FIGS. 4 and 5)